When I first experimented with astral projection i heard shrieking and experienced a dark fear like it was not safe or something. When i think of why i can only say, when i did end up projecting successfully i was just not the type of person to be limited by normal beliefs and observations and that has made some of my astral-based realisations rather scary. for example i have had robert bruce's presence enter my being doing unfunny things in response to an observation made in the astral.

I can only say, i think your higher self is just urging you patience and caution and, like me, you will project comfortably in the end, but there are definately some mature spiritual principles to observe before you can just do whatever you feel like. one of them being that your will is good for example. or that spirituality is a respectful practice to your family. from my own experience... just teething problems. good luck